Kidney Function Declines Faster in Black Patients

Action Points

Note that this cohort study from the Netherlands demonstrated an increased rate of progression to dialysis among black patients with chronic kidney disease compared with white patients.

Be aware that there were only 49 black patients in the study.

Even in a universal healthcare system that presumably provides equal care to all people, blacks with chronic kidney disease had faster progression to end-stage renal disease than their white counterparts, a Dutch study showed.

Starting 15 months after the initiation of pre-dialysis care, black patients were more than two-and-a-half times more likely to need renal replacement therapy (HR 2.87, 95% CI 1.29-6.41), according to Moniek de Goeij, MSc, a PhD student at Leiden University Medical Center in the Netherlands, and colleagues.

And black patients had a faster decline (by 0.18 mL/min/1.73 m2 per month) in estimated glomerular filtration rate (eGFR) during the study period, the researchers reported online in the Clinical Journal of the American Society of Nephrology.

The results suggest "that healthcare system factors have a less influential role in explaining black-white differences" in the progression of chronic kidney disease, they wrote.

"Our results may implicate that black patients with chronic kidney disease should be referred to pre-dialysis care earlier than white patients to assure timely preparation for renal replacement therapy," they wrote. "Fortunately, in the Netherlands this is already the case because our data showed that black patients had a higher eGFR at the start of pre-dialysis care than white patients."

U.S. studies have shown that among patients with chronic kidney disease, blacks more rapidly deteriorate to end-stage renal disease than whites. Proposed explanations have included differences in healthcare system factors -- like access to and quality of care -- and biological and societal factors.

To explore the issue in a country with a universal healthcare system, de Goeij and colleagues examined data from the retrospective and prospective parts of the PREPARE study, which followed adult patients with chronic kidney disease who were referred for pre-dialysis care in the Netherlands.

The analysis included 49 black patients and 946 white patients. When pre-dialysis care was initiated, the black patients were younger, were more likely to have diabetes or glomerulonephritis as primary kidney disease, and had higher proteinuria levels and a higher eGFR than the white patients.

In the first 15 months of follow-up, the risk of starting renal replacement therapy was not significantly different when they compared blacks with whites (HR 0.86, 95% CI 0.55-1.34).

From 15 months on, however, black patients had a significantly greater risk, even after adjustment for demographics, comorbidities, lifestyle factors, prescribed medication, eGFR and proteinuria at baseline, and laboratory variables.

The decline in eGFR was significantly greater in black patients overall (0.41 versus 0.23 mL/min/1.73 m2 per month), a difference seen in the subgroups of patients with diabetes and with high proteinuria levels but not in those without diabetes and with low proteinuria levels. That "may suggest that in blacks diabetes mellitus leads to more extensive damage of the kidneys causing a faster renal function decline," the authors wrote.

"In addition, it is reported that other factors, such as genetic differences, decreased production of vitamin D in blacks, and a greater incidence of low birth weight in blacks may also explain the different disease progression," they wrote, noting that further research is needed to definitively identify the mechanisms underlying the faster progression of disease in black patients.

The researchers acknowledged that the study was limited by the use of data pooled from the retrospective and prospective PREPARE cohorts, the assumption that patients with missing race data were white, and the lack of information on area deprivation and on the group of patients who were not referred for pre-dialysis care.

PREPARE-I and PREPARE-II were funded by an unrestricted grant from Amgen BV, and PREPARE-II was also supported by a grant from the Dutch Kidney Foundation. One of the authors received a research fellowship from the European Renal Association-European Dialysis and Transplant Association.

The authors reported that they had no conflicts of interest.

Reviewed by F. Perry Wilson, MD, MSCE Instructor of Medicine, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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